The battle of Phyle (403 BC) was the first of three battles that saw the Athenian democrats led by Thrasybulus overthrow a Spartan-supported oligarchy that was then ruling in Athens.
In the aftermath of defeat in the Great Peloponnesian War the democratic system at Athens was replaced by a new Spartan-backed oligarchy, largely imposed on the city by the Spartan leader Lysander. Power was held by the Council of Thirty, led by Critias, and supported by a garrison of 700-750 Spartan hoplites commanded by the harmost Callibius. These 'Thirty Tyrants' cut down the franchise, splitting the previous citizen body into a privileged 'Three Thousand' and an unarmed, disenfranchised majority. They murdered prominent democrats, and then as the money began to run short turned on the wealthy, confiscating their money and murdering many of them. Others fled into exile, including the successful commander of the later stages of the war Thrasybulus, who fled to Thebes. Wealthy non-citizens, the metics, were a particular target. The blood bath began to cause arguments within the thirty, but Critias arrested and murdered his main opponent Theramenes. Around 1,500 people were killed during this purge, and all former citizens not picked to join the 'Three Thousand' were expelled from the city.
Many of these exiles ended up at Thebes, where they joined Thrasybulus and Anytus. At the head of a small force of seventy democrats, these men crossed back into Attica, and seized the unoccupied fort at Phyle, north-west of Athens in the southern foothills of Mount Parnes. The leaders of the Thirty realised that this was a real challenge to their power - if the rebels were allowed to establish themselves at Phyle then they would attract an increasing number of other exiles.
This was the first real test of their regime, and things didn’t go well. The Three Thousand were mobilized, and marched to Phyle. Soon after they reached the fort, some of the younger members of the Three Thousand attempted to attack the fortress, but they were forced to retreat without achieving anything.
When the Thirty arrived they decided to besiege Phyle, but the weather intervened. This was all happening in the middle of winter, and overnight a snow storm made the attacker's position very uncomfortable. The defenders of Phyle were also active, and carried out raids on the Oligarch's camp. The Thirty were forced to abandon the siege and returned to Athens.
Now the Thirty turned to their Spartan troops. Callibius, most of his men, and two divisions of Athenian cavalry were sent out to blockade the Democrats at Phyle and protect them from plundering nearby farms. The Spartans took up a position a mile and a half from the fort, from where they could block access to more fertile areas.
By now Thrasybulus had around 700 men at Phyle, and he decided to go onto the offensive. Overnight he advanced from Phyle to a position close to the Spartan camp. Just before dawn, as the Spartans and their Athenian allies were just waking and going around their normal business, Thrasybulus ordered his men to charge. The Spartans were caught entirely by surprise. Some were killed in the initial attack, and the rest fled. According to Xenophon move than 120 of the Spartan hoplites were killed, presumably many in the pursuit, along with three of the Athenian cavalrymen, caught in their beds. Amongst them was one named Nicostratus and known as 'the beautiful'.
In the aftermath of this victory Thrasybulus had a victory trophy erected and then returned to Phyle. By the time the rest of the Athenian cavalry arrived from the city the camp was empty, so after allowing the dead to be retrieved they returned to Athens.
In the aftermath of this defeat the Thirty decided to prepare a refuge at Eleusis, expelling most of the population, a sign that they were beginning to lose their nerve. They also approached Thrasybulus to see if they could win him over to their side, but their offer of a place amongst the Thirty was rejected.
In contrast the Democrats were greatly encouraged by this success. Their numbers rose to around 1,000, and Thrasybulus decided to occupy Piraeus, the port of Athens, and now a hotbed of democratic support after the Thirty exiled many of their opponents there.